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Rural Industries Research & Development Corporation
Summary of full report
by DC Garvey and PB Cooper
June 2001
RIRDC Publication No 01/084
RIRDC Project No. PTT-1A, PTT-2A
Executive Summary
Perigord Truffles of Tasmania Pty Ltd (PTT) was formed in 1992 to exploit the opportunity of producing and marketing the highly valued and sought after gourmet food product known as the French black truffle or Perigord truffle
The French black truffle, which is the fruiting body of the fungus Tuber melanosporum, grows in a symbiotic relationship with oak and hazel trees and has been traditionally produced in regions of France, Italy and Spain for over a millennium
The truffles which are formed in the top 20 cm of the soil are harvested manually after using dogs to detect their presence by the perfume they emit at maturity which occurs in the northern hemisphere winter months of December, January and February
PTT recognised the opportunity to produce and market fresh French black truffles T. melanosporum in the southern hemisphere winter months of June, July and August
An initial study trip to France in 1992 by the directors highlighted areas of research, which were important to achieving the objective of successfully producing and marketing French black truffles
These were:
Identification and examination of
some introduced and endemic Australian ectomycorrhizal fungi and their
ability to compete with T. melanosporum in establishing truffières
in Tasmania;
Developing an understanding of the
market both domestically and internationally, by investigating the supply
chain and relationships between producers, wholesalers and consumers as
either a fresh or value added product; and
Identifying impediments or limiting
factors to production in Europe, such as irrigation methods and scheduling
weed control in truffières and manipulation of some nutrients
Since 1993 PTT have been conducting a program to address these key research issues
Study Trips to France
The directors determined that if a French truffle industry was to be successfully established in Tasmania it was essential to gain a complete understanding of the industry in France
Three research trips to France were made by the directors of PTT to confirm the reality of the opportunity, assess the likelihood of obtaining the technology necessary to produce trees inoculated with T. melanosporum and develop distribution channels for marketing truffles
PhD Thesis
A PhD study was undertaken by Dr. Daryl Brown addressed the following key areas of research:
Ectomycorrhizal fungi associated
with hazel in Tasmania, Australia;
Effect of applied lime on T.
melanosporum and other introduced ectomycorrhizal fungi;
Effect of applied lime on T.
melanosporum and other ectomycorrhizal fungi forming mycorrhiza with
hazel;
The effect of pH and calcium on
competition between T. melanosporum and other ectomycorrhizal fungi;
The effects of the interaction between
lime and phosphorus on competition between T. melanosporum and other
ectomycorrhizal;
Survey of ectomycorrhizal fungi
in a Tasmanian truffière; and
Identification of (Tuber) mycorrhiza
using DNA finger printing
The key findings from the thesis were:
The research indicated that there
is a range of endemic fungi in Tasmania soils that may be potential competitors
to T. melanosporum;
The study showed that a percentage
of the endemic fungi have a reduced activity and competitiveness at higher
soil pH levels; and
pH has a more significant affect
on the colonisation of T. melanosporum than calcium
Herbicide Evaluation
The objective in Tasmanian truffières is to establish a strip of grass and clover between the rows of trees rather than having bare earth. Herbicide use is necessary to control the weeds around the trees to avoid competition for nutrients and soil moisture
PTT established a trial to assess the effects of the use of two herbicides on T. melanosporum mycorrhiza on hazels in Tasmania. The research indicated that applying relatively high rates of the herbicides to the soil at the base of the hazel seedling did not impact the level of colonisation by T. melanosporum. Furthermore, soil type did not appear to influence the effect of the herbicides on T. melanosporum colonisation
The findings of the experiment have enabled Perigord Truffles of Tasmania to develop a weed control strategy that gives flexibility both in total weed control and in the manipulation of desirable species within truffières
Irrigation Trial
PTT conducted a trial on two commercial truffières in Tasmania to determine if there is correlation between soil moisture and mycorrhizal root development. If a relationship could be determined it would have a significant impact on the irrigation scheduling of the commercial truffières established in Tasmania. Potentially it could be a significant factor in the commencement of early truffle production
The trial conducted over two seasons 1996-98 used two irrigation monitoring systems, to determine the soil moisture levels under three different water application rates and the effect on mycorrhizal activity
Three irrigation application rates were used using three different output Dan 2001 micro jet low pressure sprinklers. The three applications were 35 litres/hour, 70 litres/hour and 105 litre/hour respectively
The results of the trial showed no significant difference between the mycorrhizal development under the three different treatments
Although the results of the experimentation were inconclusive the information generated by recording soil moisture levels was very important
In both truffières the data clearly indicated that there were wide variations in soil moisture levels particularly in the first year. The trial strongly indicated the benefits of using either form of monitoring equipment. Perigord has through the experience gained been able to convey to its joint venture farmers the importance of timely reading and recording of probes and tensiometers with respect to irrigation scheduling
Tree Growth Trial
The objective of the tree growth trial was to investigate the effects of increasing tree growth rate on the level of mycorrhization and therefore reducing the time from out-planting to the commencement of truffle production
The key aims of the experimentation which were established on two commercial truffières in Tasmania were:
To determine if increased tree growth
would result in increased competition from endemic fungi;
To investigate the effects of increasing
tree growth rate on the level of mycorrhization; and
To reduce the time from out-planting
to truffle production
In August 1998 replicates of four rows of ten trees were selected in each truffière
Three treatments of phosphorus and nitrogen were applied in split applications to the trees. In addition an artificial windbreak was constructed to assess the effect of wind on the growth rates of the trees
The key findings of the trial were:
No significant difference in the
rate of mycorrhizal growth under any of the treatments;
No reduction in the mycorrhiza as
a result of applying the phosphorus and nitrogen;
Whilst a small number of other unidentified
mycorrhiza were observed, there was no significant effect between the treatments;
There was no significant response
in tree growth to the phosphorus and nitrogen treatments compared to the
controls at either site; and
A limited response in tree growth
to the windbreak treatment in one truffière
The above findings have allowed PTT to proceed with confidence in further assessing the relationship between fertiliser applications and the response in tree growth rates
The production of 3 kg of French truffles on multiple sites in the winter of 2000 has confirmed PTTs success in achieving its goals. The company has confirmed its ability to transfer and apply the necessary technology and had its theories with respect to climate, geography and geology tested and confirmed. PTT has seen the creation of a unique production agreement with its joint venture growers that has withstood the test of time and has successfully harvested and marketed a premium quality product to an excited and receptive market at a price almost double its budget
The nature of the joint venture agreement
between PTT and truffle growers results in both the company and farmers
sharing equally in any of the benefits gained from the research and development
program
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